A perfect gas goes from state A to another state B by absorbing 8 x `10^5` J of heat and doing 6.5 x `10^5` J of external work. It is now transferred between the same two states in another process in which it absorbs `10^5` J of heat. Then in the second process,

Options

A. work done by gas is `10^(5)` J
B. work done on gas is `10^(5)` J
C. work done by gas is `0.5 xx 10^(5)` J
D. work done on the gas is `0.5 xx 10^(5)` J

Answer

D

Explanation

`dU = dQ -dW = (8 xx 10^(5) - 6.5 xx 10^(5)) = 1.5 xx 10^(5)` J
`dW = dQ- dU = 10^(5) -1.5 xx 10^(5) = -0.5 xx 10^(5)`J
`-ve` sin indicates that work done on the gas is `0.5 xx 10^(5)` J.